Image forming devices that form color images by superposing images in a plurality of colors formed respectively by a plurality of process units have conventionally performed misregistration correction to adjust color registration. An example of misregistration correction is a process of forming a registration mark in each color, acquiring the amount of offset between the mark of a reference color and the mark of an adjustment color, and adjusting the position of the adjustment color based on a correction value corresponding to the mount of offset.
Various documents have been published on adjusting images, such as the misregistration correction described above. One image forming system known in the art employs a different execution condition for each type of print data in order to determine whether or not to execute the process to form registration marks. With this image forming system, the execution condition is more likely to be met for types of print data in the order of images, drawings, and text (see Japanese Patent Application Publication No. 2005-181534).